Along with the prevalence of image processing apparatuses, everyone can easily copy and transmit document images. However, although such easy copying and transmission improve the user's convenience, they also pose a problem of leakage of information such as copying and transmission of secret information. To solve this problem, an image processing apparatus which stores all read image data in a recording device upon copying or transmission is available. With such apparatus, the administrator can track down a leakage source by checking the image processing apparatus which read a document image of information leaked.
Japanese Patent Laid-Open No. 2004-118243 describes an apparatus which stores a history including information printed by a printer, a printing date and time, a user who made printing, and the like, and allows to search for stored information. This reference discloses an apparatus which has a deterrence over illicit information leakage, since the history can be referred to if perchance information has leaked.
However, in order to store all input and output image data in the recording device, a large-capacity recording device is required. In addition, image data in which some characters or images have been changed by editing a previously copied document image is stored as an image different from the previously copied document image. In other words, the storage efficiency is very poor.